1. Field of the Invention
The invention relates to a method for the intermediate storage of documents which are supplied from a system arranged upstream to a system arranged downstream. The invention furthermore relates to a device for performing the method, comprising a transport device with transport elements configured to transport the documents through the device.
2. Description of the Related Art
It is known to supply documents or document sets coming, for example, from a folding device or a feeder, to a system arranged downstream, for example, a system for enveloping the documents, a packaging or foil-wrapping device or the like. Between the upstream and downstream systems an intermediate storage device is provided which is in the form of a chain conveyor. The documents or document sets coming from the system upstream are successively deposited on the chain conveyor. When a document or a document set is required in the system downstream, the chain conveyor is switched on and the document or document set is supplied to the system downstream. Depending on the number of documents contained in the document sets, the document sets are not supplied by the system upstream of the chain conveyor in such numbers as required by the system downstream. This has the consequence, that empty positions result on the chain conveyor which cause a reduction of capacity of the device.
It is an object of the present invention to design the method and the device of the aforementioned kind such that the capacity of the device is increased.
In accordance with the present invention, this is achieved in regard to the method in that the documents are transferred to the downstream system independently of the supply cycle of the system upstream.
In accordance with the present invention the object is achieved in regard to the device in that the transport device comprises a continuously driven transport unit at the input side and a cycled or intermittently driven transport unit at the output side.
According to the method of the invention, the documents are transferred to the system downstream independently of the supply cycle of the upstream system. For this purpose, the transport device is provided with two independently driven transport units. The transport unit positioned at the input side is operated continuously, so that the documents coming from the upstream system are immediately transported into the intermediate storage device. The transport unit provided at the output side, on the other hand, is operated in a cycled fashion (intermittently). In accordance with the document demand of the system arranged downstream, the documents are supplied by the cycled transport unit to the system arranged downstream. Since at the input side the transport unit is operated continuously, the documents can be supplied in larger numbers than are released at the exit side. With the method according to the invention and the device according to the invention, a decoupling of supply and removal of the documents is realized. Accordingly, when in the upstream system the sets of documents have different numbers of sheets, it is avoided that empty spaces between the documents result in the intermediate storage device. In this way, a very high capacity of the intermediate storage device according to the invention results. The upstream systems can thus be continuously driven even when fluctuations of the number of sheets belonging to a document set occur because the transport unit at the input side is also continuously driven.